Federal Health Minister Nicola Roxon says Opposition MPs should cross the floor to support both of the Government's plain cigarette packaging bills.

Ms Roxon says the legislation will be debated and voted on in the House of Representatives today.

Opposition Leader Tony Abbott has pledged support for one of the bills, but not the one which allows changes to trademark rules.

Ms Roxon is urging Mr Abbott to change his mind.

"I am confident from all of the public comments and private discussions that I've had that there is very widespread support in the House of Representatives for both pieces of legislation to introduce plain packaging for cigarettes," she said.

"I hope that Mr Abbott will put aside his reservations and show that he can lead the Liberal Party in the way that we are leading the world."

Ms Roxon expects both bills to pass, but she says Coalition MPs who disagree with Mr Abbott should defy him.

"Every single person in the House of Representatives needs to consider this legislation carefully, they need to think about the impact that tobacco-related disease has on their constituents, their families and friends," she said.

"And if they believe that doing all we can to tackle tobacco is a good idea then I will call on them to vote with us."